People are living longer than ever. According to a 2015 World Health Organisation report, Japanese live the longest, with an average life expectancy of 84, while Americans can expect to live to 77. At the same time, it is an obvious fact that some people live much longer than other people. There is inequality in mortality.
A more surprising discovery is that there is a strong link between mortality and IQ: Higher intelligence means, on average, a longer life. This relationship has been extensively documented by Ian Deary and his colleagues at the University of Edinburgh using data from the Scottish Mental Surveys.
In 1932, the Scottish government administered an IQ test to nearly all 11-year old children attending school on a single day. More than sixty years later, focusing on the city of Aberdeen, Deary and colleague Lawrence Whalley set out to identify who from the cohort was still alive, at age 76. The results were striking: A 15-point IQ advantage translated into a 21 per cent greater chance of survival. For example, a person with an IQ of 115 was 21 per cent more likely to be alive at age 76 than a person with an IQ of 100 (the average for the general population).
The link between IQ and mortality has now been replicated in upwards of 20 longitudinal studies from around the world, and has given rise to the field of cognitive epidemiology, which focuses on understanding the relationship between cognitive functioning and health.
Evidence suggests that genes may contribute to the link between IQ and living a long life. The results of a new study by Rosalind Arden and colleagues in the International Journal of Epidemiology provide the first evidence for this hypothesis.
Arden and colleagues identified three twin studies (one from the US, one from Denmark, and one from Sweden) in which both IQ and mortality were recorded. They then performed statistical analyses to estimate the contribution of genetic factors to the IQ-lifespan relationship. The results were clear and consistent: genes accounted for most of the relationship.
Source: www.scientificamerican.com
